Question | Answer |
secondary pollutant | Harmful chemical formed in the atmosphere when a primary air pollutant reacts with normal air components or other air pollutants. Compare primary pollutant. |
smog | Originally a combination of smoke and fog but now used to describe other mixtures of pollutants in the atmosphere. See industrial smog, photochemical smog |
stratosphere | Second layer of the atmosphere, extending about 17-48 kilometers (11-30 miles) above the earth's surface. It contains small amounts of gaseous ozone (O3), which filters out about 95% of the incoming harmful ultraviolet (UV) radiation emitted by the sun. C |
temperature inversion | Layer of dense, cool air trapped under a layer of less dense, warm air. This prevents upward-flowing air currents from developing. In a prolonged inversion, air pollution in the trapped layer may build up to harmful levels. See radiation temperature inver |
Acid deposition | The falling of acids and acid-forming compounds from the atmosphere to the earth's surface. Acid deposition is commonly known as acid rain, a term that refers only to wet deposition of droplets of acids and acid-forming compounds. |
air pollution | One or more chemicals in high enough concentrations in the air to harm humans, other animals, vegetation, or materials. Excess heat and noise are also considered forms of air pollution. Such chemicals or physical conditions are called air pollutants. See |
atmospheric pressure | A measure of the mass per unit area of air. |
buffer | Substance that can react with hydrogen ions in a solution and thus hold the acidity or pH of a solution fairly constant. |
carbon oxides | Carbon and oxygen compounds |
industrial smog | Type of air pollution consisting mostly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid formed from some of the sulfur dioxide, and a variety of suspended solid particles. Compare photochemical smog. |
ozone (O3) | Colorless and highly reactive gas; a major component of photochemical smog and also found in the stratosphere where it protects life by filtering out most harmful UV radiation from the sun. |
ozone depletion | Decrease in concentration of ozone in the stratosphere. |
ozone layer | Layer of gaseous ozone in the stratosphere that protects life on earth by filtering out most harmful ultraviolet radiation from the sun. |
volatile organic compounds (VOCs) | Organic compounds that exist as gases in the air. Most are hydrocarbons |
sulfur dioxide (SO2) | Colorless gas with an irritating odor. About two-thirds (and as high as 90% in urban areas) comes from human sources, mostly combustion of sulfur-containing coal in electric power and industrial plants and from oil refining and smelting of sulfide ores. |
sulfuric acid (H2SO4) | Formed in the atmosphere from sulfur dioxide. As microscopic suspended droplets, it is a component of acid deposition. |
nitric acid (HNO3) | Formed when NO2 reacts with water vapor in the air. It is a component of acid deposition that returns to the earth and can damage trees, soils, and aquatic life in lakes. |
nitrogen oxides (NOx) | Nitrogen oxide and nitrogen dioxide collectively. These gases play a role in photochemical smog and can irritate the eyes, nose, throat, and lungs; aggravate asthma and bronchitis; and increase susceptibility to respiratory infections by impairing the imm |
PANs | Peroxyacyl nitrates. Group of chemicals found in photochemical smog. |
photochemical smog | Complex mixture of air pollutants produced in the lower atmosphere by the reaction of hydrocarbons and nitrogen oxides under the influence of sunlight. Especially harmful components include ozone, peroxyacyl nitrates, and various aldehydes. Compare indust |
Living machine Sewage | A purification process in which sewage flows into a passive solar greenhouse or outdoor site containing rows of large open tanks populated by an increasingly complex series of organisms. |
Water pollution | Any physical, biological, or chemical change in surface water or groundwater that can harm living organisms or make water unfit for certain uses. |
Point source | Discharge pollutants at specific locations through drain pipes, ditches, or sewer lines into bodies of surface water. |
Nonpoint source | Large or dispersed land areas such as crop fields, streets, and lawns that discharge pollutants into the environment over a large area that cannot be traced to any single site of discharge. |
Eutrophication | The name given to the natural nutrient enrichment of a shallow lake, estuary, or slow moving stream, mostly from runoff of plant nutrients such as nitrates and phosphates from surrounding land. |
Cultural eutrophication | Human activities near urban or agricultural areas that can greatly accelerate the input of plant nutrients to a lake. |
Septic tank | Underground tank for treating wastewater from a home in rural and suburban areas. Bacteria in the tank decompose organic wastes, and the sludge settles to the bottom of the tank. The effluent flows out of the tank into the ground through a field of drainp |
Primary sewage treatment | A physical process that uses screens and a grit tank to remove large floating objects and allow solids such as sand and rock to settle out. Then the waste stream flows into a primary settling tank where suspended organic solids settle out as sludge. |
Secondary sewage treatment | A biological process in which aerobic bacteria removes as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes. |
Advanced or Tertiary sewage treatment | Specialized chemical and physical processes that reduce the amount of specific pollutants left in wastewater after primary and secondary sewage treatment. This type of treatment usually is expensive. |
Tertiary (higher-level) consumers | Animals that feed on animal-eating animals. They feed at high trophic levels in food chains and webs. Examples are hawks, lions, bass, and sharks. Compare detritivore, primary consumer, secondary consumer. |
Biological oxygen demand (BOD) | Amount of dissolved oxygen needed by aerobic decomposers to break down the organic materials in a given volume of water at a certain temperature over a specified time period. |
Dissolved oxygen (DO) content | Amount of oxygen gas (O2) dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water. |
Sludge | Gooey mixture of toxic chemicals, infectious agents, and settled solids removed from wastewater at a sewage treatment plant. |
Oxygen-demanding wastes | Organic materials that are usually biodegraded by aerobic (oxygen-consuming) bacteria if there is enough dissolved oxygen in the water. |
Agricultural Activities | Leading cause of water pollution. |
Industrial Facilities | Another source of water pollution from a variety of harmful inorganic and organic chemicals. |
Mining | Surface mining disturbs the earth’s surface, creating a major source of eroded sediments and runoff of toxic chemicals |
Oxygen Sag Curve | This curve is represented from the breakdown of degradable wastes by bacteria depleting dissolved oxygen |
Harmful Algal Blooms | When large quantities of nitrate and phosphate plant nutrients are introduced it can cause this explosive growth of harmful algae. |